The present invention relates to the field of fluid pressure units, in particular a hydraulic motor or hydraulic pump, comprising rotating and stationary elements such as a rotor and a stator and a support of the rotor with respect to the stator, where those elements are arranged to allow rotational motion around a geometrical axis and are fixed to each other in the direction of this axis, a cam ring which is fastened to the stator, a cylinder block as a part of the rotor in which cylinder bores are made and disposed substantially in a radial direction and slidable pistons mounted in said cylinders which are abutted on the cam rings by rollers.
Such radial piston fluid pressure units are known from DE 3834878 A1, for example. These known pump and motor mechanisms are subjects of continuous research with the intention of reducing their space requirements in radial and axial directions. The axial space requirement of the mechanism is substantially affected by the bearing arrangement. So the primary activities have been concentrated in this area and several configurations of bearing arrangement have been established. It is essential to ensure support in both axial and radial directions. The radial load component results mainly from external forces acting on the mechanism, while axial load components may also be created from internal system dependent forces.
It is an object of the invention to propose a novel system configuration in which this internal axial force component is considerably reduced and which enables the use of a smaller dimensioned bearing arrangement thus leading to a lower requirement of axial and radial space.
It is a further object of the invention to permit the axial force component acting on the bearing arrangement to result from the known assembly of the control device which controls the flow connection of the cylinders to both of the pressure ports of the mechanism.